Tubular fiber plug for walls and the like



J. J. RAWLINGS TUBULAR FIBER PLUG FOR WALLS AND THE LIKE Filed July 1, 1924 Patented Jan. 27, 1925.

UNITED STATES PATENT OFFICE.

JOHN JOSEPH RAWLINGS, OF LONDON, ENGLAND, ASSIGNOR OF ONE-HALF TO THE RAWLPLUG COMPANY, LIMITED, LONDON, ENGLAND.

TUBULAR FIBER PLUG FOR WALLS AND THE LIKE.

Application filed July 1, 1924. Serial No. 723,573.

To a7Z whom it may concern:

Be it known that I JOHN JOSEPH RAWL- INGS, a subject of the king of Great Britain, residing at London, England, have invented I new and usefullmprovements in Tubular Fiber Plugs for Walls and the like, of which the following is a specification.

This invention relates to tubular plugs for insertion in brick, stone, or other hard 10 building material and intended as fixings for screws, and more particularly to such tubular plugs made of jute, flax, asbestos, hair or other fibrous material. In this type of plug, the uired grip is obtained by the expansion 0 the wall of the plug produced by the insertion of the screw.

According to the present invention, the plug is made from twisted strands of fiber or cord or paper or the like, arranged in spiral formation, and cemented or otherwise held together to form a tube having spiral lines of weakness. The spiral arrangement of the strands is contrary to that of the twist of the individual strands. That is to 95 say, if the strands have a. left hand twist, then the spiral arrangement of the strands forming the tube is rlght-handed, and vice versa.

Moreover it is preferable that the spiral arrangement of the twisted strands forming the plug shall be in the contrary direction to that of the screw with which the plug is to be used. This arra ment avoids or minimizes the cutting of t e cord strands by the threads of the screw.

The strain which resists the withdrawal of a lug from a. hole in which it is fixed is distri uted circumferentiall round the wall of the hole, and any pu l on the screw tends to shorten the plug and expand its 40 diameter and so sets up a tighteningl action of the strands against the wall of t e hole, thereby ensuring increased grip. The pitch of the spiral arrangement may be varied considerably.

The accom anying drawings illustrate four forms of plug made according to the present invention.

Figure 1 shows a plug made from six twisted strands or cords. .m Figure 2 shows a plug made from six large cords combined with a similar number of smaller cords; and

Figure 3 shows a plu double layer of twisted cor s.

Figure 4 shows a plug made from soft twisted cords or strands which assume a segmental form.

Each of the strands a, a consists of twisted fiber, paper or the like, or cord, and the several strands are wound side by side in spiral formation as indicated to make a tubular plug, the whole being cemented and pressed together in a known manner. The strands are preferably twisted right- 6 handed; the best number of strands to use is six which leaves a centre hole at the core of the same diameter as the individual cords. The number of strands may however be varied with good results. The strands a may be twisted to form the plugs whilst immersed in glue or cement, or, they may first be twisted together to form the tube, after which the tube is immersed in lue or cement mixture, drawn through ies, dried and hardened and then cut into plugs of the required len h. This last described method has the a vantage of preventing access of the glue or cement into the interior of the plug and so reducing the friction when a screw is turned into position in the plug.

When the plugs are of relativel large diameter the spaces between a joining strands or cords should be filled so that the plug can obtain the maximum surface grip, and to do this the interstices may be filled with thick glue or cement that may be loaded with earthy or fibrous matter, or the space may be filled with smaller sectioned cord; 12, b as shown in Figure 2.

Lar e plugs may have two layers of twiste strands or cords, as shown in Figure 3. lhese layers may be twisted in the same or in opposite directions.

The plugs may be made in a continuous comprising a length, from cords or'strands fed from a series of spindles mounted in a rotary frame spirally in a tubular formation and held toi gether by an adhesive cement.

2. A socket for lining a hole for rece1vin a screw, said socket comprising a plura it of strands of fibrous material in whic the fibers are twisted in the same direction, and the said strands are twisted in the opposite direction in a spiral formation to form a tubular structure.

3. A socket for lining a hole for'receivin a screw, said socket comprising a plura ity of strands of fibrous material in which the fibers are twisted in the same direction, and the said strands are twisted in the opposite direction in a spiral formation to form a tubular structure in which the adjacent strands are weakly held together along spiral lines. a

4. A socket for lining a hole for receivn a screw said socket comprising a plurality of strands of fibrous material arran ed spirall hell? together i; of contact.

JOHN JOSEPH RAWLINGS.

Witneaes:

Comm) Aimom, Hnnnm A. Busrox.

in a tubular formation and y glue along the spiral lines 

